Recently, thin film magnets in minute size (the thickness is about several micrometers to several hundreds of micrometers) have become prepared by physical film formation methods, e.g., sputtering or laser deposition, and have been used in the fields of micromachines or sensors (Patent Document 1). In the application of employing such thin film magnet in the fields of micromachines or sensors, in order to prepare a targeted device, a magnetic circuit is necessarily designed on the base of the magnetic flux leakage due to the remanent magnetization of the thin film magnet, and the distribution of the remanent magnetization (i.e., the remanent magnetization in microregions) of the thin film magnet need to be precisely measured with a resolution of a submillimeter level or less.
So far, a B-H curve tracer or a VSM (vibrating sample magneto-meter) has been used in measuring the magnetic characteristics of the magnetic sample. However, these measurement devices can only measure the average magnetic characteristics of the magnetic sample which is the object to be measured, and cannot measure the distribution of the magnetic characteristics, i.e., the characteristics in a microregion.
A method is also considered in which the magnetic sample which is the object to be measured is divided by cutting process or the like and measured by a VSM or the like so that the magnetic characteristics in a microregion is measured. However, the inherent magnetic characteristics of the magnetic sample cannot be measured due to the damage to the surface layer of the magnetic sample caused by the process.
In order to measure the magnetic characteristics in a microregion of a magnetic sample without processing the magnetic sample, a MFM (magnetic force microscopy), a SHPM (scanning hall probe microscopy) or the like is used.
The MFM uses the measuring head composed of a magnetic substance to scan the surface of a sample, so that the magnetic characteristics in a microregion can be precisely measured. However, as it is necessary to move the measuring head of the MFM close to the surface of the sample, and unlike the B-H curve tracer, the sample cannot become a part of the closed magnetic circuit, the measurement will be definitely affected by the demagnetizing field Hd due to the magnetic pole present on the surface of the magnetic sample.
As the effect of the demagnetizing field Hd largely depends on the shape of the sample, and in a thin plate magnetic sample such as a uniformly magnetized film magnet, the demagnetizing field Hd is substantially equal to the spontaneous magnetization J of the sample, the magnetic flux cannot be taken to the outside of the sample. That is, it is difficult to evaluate the magnetic characteristics of the uniformly magnetized thin plate magnetic sample by using a MFM.